In recent years, in JP-A-57-63310, JP-A-58-83016, JP-A-59-58010, JP-A-60-44507 and others, there have been proposed, for polymerization of alpha-olefin, a number of highly active carrier-supported type catalyst systems comprising solid constituents containing indispensably magnesium, titanium, a halogen element and an electron donor, an organometal compound of a metal of I-III groups in Periodic Table, and an electron donor. Further, in JP-A-62-11705, JP-A-63-259807, JP-A-2-84404, JP-A-4-202505 and JP-A-4-370103, there have been disclosed other polymerization catalysts characterized by containing a specific organosilicon compound as an electron donor. For example, JP-A 2-84404 discloses a method that employs a cyclopentyl(alkyl)dimethoxy silane or di(cyclopentyl)dimethoxy silane as an electron donor. The catalyst systems using such the silicon compounds, however, are not always excellent in hydrogen response. JP-A 63-223008 discloses a catalyst system that employs a di(n-propyl)dimethoxy silane as an electron donor excellent in hydrogen response, which is though not particularly satisfactory at stereoregularity and causes a problem because an α-olefin polymer can not has an increased solidity.
JP-A 9-40714 proposes an alkoxy silane compound having an aliphatic amino substituent. JP-A 8-3215, 8-100019 and 8-157519 propose methodes of manufacturing α-olefins using an alkoxy silane having an aliphatic amino substituent as a catalyst component, which are though not always satisfactory at hydrogen response. JP-A 8-143620 proposes a method of manufacturing α-olefin using a dialkoxy silane having two aliphatic amino substituents as an electron donor, which is though not always satisfactory at polymerization activity and stereoregularity in performance.
JP-A 8-100019 and 8-157519 propose methodes of manufacturing α-olefin polymers having a small molecular weight (or large MFR) using a dialkoxy silane having a hydrocarbon group-containing amino substituent and a hydrocarbon group as a catalyst component. They describe examples of polymers with MFR of 60 g/10 min at most, which are not always satisfactory at hydrogen response in performance.
JP-A 8-120021, 8-143621 and 8-2316663 disclose methodes using cyclic amino silane compounds. When these specifically described compounds are employed as catalyst components, they exhibit high stereoregularity but are not always adequately satisfactory at hydrogen response. In addition, a problem occurs because a molecular weight distribution is not always wide.
JP-A6-25336, 7-90012 and 7-97411 disclose methodes using a nitrogen atom-containing heterocyclic substitutional organosilicon compound that includes a silicon atom directly bonded to any carbon atom in a heterocycle, but they fail to describe any molecular weight distribution. JP-A 3-74393 and 7-173212 disclose methodes using a monocyclic amino group-containing organosilicon compound but fail to describe any molecular weight distribution.
A propylene polymer with a wide molecular weight distribution and high stereoregularity can be produced in such a method that can be considered as comprising: producing a high stereoregularity and low molecular weight propylene polymer and a high crystallinity and high molecular weight propylene polymer previously using a conventional method; and then melting and blending them in a desirable ratio. In this case, production of the propylene polymer with a relatively low molecular weight and wide molecular weight distribution makes it extremely difficult to melt and blend the low molecular weight propylene polymer and the high molecular weight propylene polymer uniformly, resulting in problems associated with gel generation, for example.
JP-A 2000-63417 discloses a method that provides an α-olefin polymer with high activity, high hydrogen response, high stereoregularity and wide molecular weight distribution. This system, however, worsens hydrogen response and greatly sacrifices stereoregularity when the molecular weight distribution is extended to an aimed value. Thus, an improvement is required.
A high hydrogen response is also important. Namely, when hydrogen coexists in a polymerization system to adjust the molecular weight, a low hydrogen response requires a large amount of hydrogen. Therefore, as described above, the use of an excessive chain transfer agent such as hydrogen is required to produce a low molecular weight polymer. Consequently, it is required to lower a polymerization temperature during bulk polymerization in a polymerization device having a pressure-proof limit and reduce a monomer partial pressure during gas-phase polymerization, resulting in an ill effect exerted on the productivity rate disadvantageously.
JP-A8-143620 according to the applicant proposes a method of manufacturing an α-olefin using a dialkoxy silane having two aliphatic amino substitutions as an electron donor. This method, however, may lower stereoregularity (H. I.) and polymerization activity on production of polymers with MFR of 200 or more and is not always satisfactory at performance.
JP-A 8-3215 and 9-40714 also according to the applicant propose an alkoxy silane compound having an aliphatic amino substitution and methodes of manufacturing stereoregularity and melt fluidity (that is, high MFR) using the same. The silane compound described therein, however, is only a dialkoxy silane having both of one amino group containing hydrocarbon group and one hydrocarbon group, that is, a dialkoxy silane represented by R1Si(OR2)2(NR3R4). In addition, specifically exemplified compounds are only dimethoxy silanes, for example, a methyl(diethylamino)dimethoxy silane. As for a trialkoxy silane represented by Si(OR2)3(NR3R4), no specific compound is exemplified. The obtained polymerization result is not always satisfactory because a larger MFR results in a lower stereoregularity.
JP-A 2000-63417 and 2000-204111 disclose methods using organosilicon compounds and polycyclic amino organosilicon compounds. When the compounds described therein are employed as catalysts, they exhibit high stereoregularity but are not always satisfactory at hydrogen response.
The carrier catalyst system using the electron donor described earlier is not always satisfactory at balanced polymerization activity, stereoregularity and hydrogen response in performance, and accordingly a further improvement is required.
In recent years, in the field of injection molding mainly for automobile materials and household electrical materials, for the purpose of thinning and light-weighting of products, α-olefin polymers with high melt fluidity, high solidity and high heat resistance are increasingly needed. It is important to use a catalyst with a high hydrogen response during polymerization to produce such α-olefin polymers. Specifically, it is general to allow hydrogen to coexist as a chain transfer agent in the polymerization system to adjust the molecular weight of the α-olefin polymer. In particular, to increase the melt fluidity of the α-olefin polymer, hydrogen is required to lower the molecular weight. Melt flow rate is employed as an index of the melt fluidity of the α-olefin polymer. The lower the molecular weight of the α-olefin polymer is related with the higher the melt flow rate. A lower hydrogen response requires a large amount of hydrogen in the polymerization system to increase the melt flow rate of the α-olefin polymer. A higher hydrogen response does not require such the amount of hydrogen as is required in the case of the lower hydrogen response to produce the α-olefin polymer with the same melt flow rate. Accordingly, the low hydrogen response requires introduction of an excessive amount of hydrogen into the polymerization system to elevate the melt flow rate of the α-olefin polymer. Consequently, for safety in a production method, the polymerization temperature in the polymerization device having the pressure-proof limit should be lowered in relation to an increased hydrogen partial pressure. This exerts ill effects on the production speed and the quality disadvantageously.
On the other hand, ethylene propylene block copolymers are widely employed for household electrical and automobile materials and required to reduce their production costs. Methodes of manufacturing ethylene propylene block copolymers include a method with the conventional catalyst system, which comprises producing an ethylene propylene block copolymer in a polymerization reactor; and then mixing and kneading a rubber component mechanically, though it has a problem because of its high cost. Therefore, in a method using multistage polymerization devices, a propylene homopolymer is produced at the first stage polymerization device, and a sufficient amount of copolymer is produced during ethylene propylene copolymerization in the following polymerization stages. In this case, such a catalyst system is strongly desired that can produce the so-called linearly polymerized block copolymer of ethylene and propylene so that the produced block polymer has sufficient fluidity.
As for the block copolymer from the conventional catalyst system, if an amount of the polymer in the following stages reaches 10% or more of the polymer in the first state, molding is substantially impossible. This is because the melt fluidity is extremely small unless the rubber component in the block copolymer (a room temperature p-xylene soluble component) has an extremely small value of [η].
As a method of manufacturing ethylene propylene block copolymers, JP-A 8-217841 also filed by the applicant discloses one, which employs a silane compound or bis(dialkylamino)silane as a component of a polymerization catalyst. JP-A8-231663 also filed by the applicant discloses another method, which employs a silane compound or bis(dicyclicamino)silane as a component of a polymerization catalyst. These methodes, however, have a subject associated with insufficient hydrogen response.
To solve the above problems associated with the prior arts, the present invention has an object to provide a catalyst for polymerizing or copolymerizing an α-olefin, catalyst component thereof, and method of polymerizing α-olefins with the catalyst, for production of α-olefin polymers or copolymers with high hydrogen response, high polymerization activity, high stereoregularity and excellent melt fluidity.